Polyvinyl fluoride (PVF), commercially available in film form, is used in a wide variety of protective and decorative applications. Typically, PVF is laminated to another surface. For example, it is often used as the top surface on aluminum or polyvinyl chloride panels used for house siding.
PVF has also been used for surfacing interior aircraft panels, bonded to a substrate that forms the basic structural component of such panels. Bloom, in U.S. Pat. No. 4,937,135, describes thick laminates of PVF and polyaryletherketoneketone (PEKK), in which the thickness of the PEKK is greater than about 625 micrometers.
These Bloom laminates are thermoformable, under the conditions described therein However, decorative aircraft interior panels are often also required to be embossed. The laminates of Bloom could be so treated in two ways.
Specifically, these laminates could be embossed upon extrusion, before the relatively thick layer of PEKK had fully cooled. In the alternative, an embossing resin could be included between the PVF and the PEKK layers. The embossing resin is a material that flows under heat and pressure, and is usually present as a 3-5 mil sheet. This type of layer permits the embossing of the PVF without heating the PEKK to its melting or softening temperature, at which the PVF would be destroyed, since the melting temperature of PEKK (305.degree. C.) is significantly higher than the decomposition temperature of PVF (200.degree. C.). While these interlayers provided satisfactorily embossed articles, the embossing resins typically generate undesirably high smoke levels upon combustion or overheating. This would make the laminates unsatisfactory in most aircraft applications.